Nobody laughed when a gossip weekly linked one of Japan's most popular comedians and variety show hosts to Japan's top crime syndicate recently. Friday magazine ran pictures of Shinsuke Shimada consorting with the “yakuza” after he himself admitted to doing so and abruptly retired last month.

The episode underlined the huge presence that gangsters still have in Japanese society despite recent attempts to curb their influence. The yakuza—as gangsters are popularly known here—are not outlawed, but police keep tabs on their activities, moving in only if they flout the law.

As a veteran who hosted several top-rated shows every week, Shimada should have known better. People like him, who have extensive links in society and a huge impact on it, are among the favourite prey of the yakuza.

So too are politicians and well-known sportsmen. Several years ago, Shimada badmouthed the yakuza on one of his shows. In response, local gangsters blasted the TV station day and night through loudspeakers. The concerned comedian asked a professional boxer with ties to the yakuza to mediate. The harassment stopped but he became beholden to the gangsters.

At a press conference, Shimada claimed that his association with the gangsters was not really serious enough to land him in trouble. But he obviously did not tell all. On September 9, Friday carried incriminating photographs showing Shimada at parties and golf tournaments involving the yakuza that suggested he and the gangsters were more than passing acquaintances. Earlier this month, Japan's police chief Takaharu Ando told reporters: “It is extremely regrettable that an entertainer who has huge social influence should mix with the yakuza.

“We will do whatever we can to help the entertainment world sever its ties with the underworld.” But some of those ties could be hard to break. Japanese gangsters, or more often their front organisations, have come to play a major role in providing the logistics needed by entertainers to stage concerts around Japan. Their numbers, although on the decline, certainly cannot be ignored.

The yamaguchi-gumi, the biggest and wealthiest syndicate in Japan, has 35,000 regular and affiliate members— almost half of Japan's gangster population—and is dominant in the western half of the country.

Although their origins are unclear, the yakuza are said to have evolved from groups of shady peddlers and gamblers in 18th century Japan. Today's syndicates are ruled by bosses who enforce a strict code of justice and demand absolute loyalty and respect from their members. The yakuza, who are fond of tattoos and demand “errant” members to amputate their small finger as an expression of apology, are a scourge to the economy in general. They rake in billions of yen in revenue from such activities as extortion, running gambling dens and sex-related businesses, illegally importing guns and drugs, manipulating the stock market, bid-rigging and bank fraud.

However, the gangster population has already slowly declined over the years, especially after a 1991 law that allowed the police to step up monitoring of syndicates. The police have also been closing in on syndicate elders . Yamaguchi-gumi's current head Shinobu Tsukasa was jailed in 2005 for illegal gun possession and released only in April.

The recession in Japan has also hit the yakuza, pushing many gangs to expand to China and Southeast Asia to link up with foreign syndicates.

But surprisingly, not everything about the yakuza is bad. The yamaguchi-gumi, for example, helped in relief efforts during the 1995 Kobe earthquake as well as the earthquake-cum-tsunami disaster in north-eastern Japan in March.

Residents who live near the yamaguchi-gumi's headquarters say young gangsters are civic-minded, helping to clean up choked drains and even sprucing up the neighbourhood. Although the yakuza refer to themselves as “chivalrous organisations”, most people see them as “anti-social forces”.

Next month, Tokyo will be among the last prefectures to enforce local laws requiring businesses to abstain from dealing with the yakuza. To publicise the new law,

Tokyo police last month descended on the Kitazawa hachiman Shrine in Tokyo's Setagaya district during its annual festival to hand out fliers to worshippers. The shrine successfully purged the yakuza from its premises 20 years ago. Since then it has counted on residents to manage the food stalls at festivals.

As chief priest Tsugihisa Yajima said: “I hope the new law will give a push to the momentum now building up towards getting rid of the yakuza.”